General: A small to medium stratified foliose lichen, corticate above and below, neither sorediate nor isidiate, lobes closely appressed, short to subrotund, averaging to 2–3 (–4) mm wide, thin. Upper surface pale yellowish green (except blackish in exposed sites), shiny. Lower surface whitish to pale tan, bearing sparse to abundant short, simple rhizines. Medulla white. Photobiont green. Apothecia located over upper surface, disc brown; spores simple, spherical, colourless, 8 per ascus.
Notes: Ahtiana is a monotypic genus. It was formerly included within Parmelia, but is more closely related to Cetraria (in the broad sense).
Reactions: Medulla C+ reddish to orangish, KC+ reddish.
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Note that individual subspecies or varietal illustrations are not always available.
